Here's what the BCS media guide says about BCS revenue sharing this year:
The net share for the automatic-qualifying team from each AQ conference will be approximately $22.3 million.
The share for each team selected at-large by one of the bowls will be $6.1 million.
The share for an automatic qualifier from one of the five non-AQ conferences (i.e., a conference without annual automatic qualification) will be approximately $26.4 million 18 percent of the net revenue. (Those conferences have elected to divide the revenue among themselves according to a formula they have devised.)
If no team from the non-AQ conferences participates, those conferences would receive approximately $13.2 million 9 percent of the net BCS revenue.
NotreDame will receive $6.1 million if it participates in a BCS game; its share will be approximately $1.8 million if it does not 1/66th of the net BCS revenue.
If Army, Navy or BYU becomes an automatic qualifier or is selected at-large, it will receive $6.1 million; if not selected, each will receive $100,000.
Each FCS conference will receive $250,000.
If Boise State or TCU had automatically qualified, that would have boosted the non-AQ conference share from $13.2 million to $26.4 million, an increase of $13.2 million. There would have been an offsetting reduction of $6.1 million because one of the at-large teams would have been displaced. So the total BCS payout went down by $7.1 million as a result of Boise State or TCU failing to automatically qualify. I assume that money will go back into the BCS pot and will slightly increase everyone's share, resulting in slightly higher payouts than those indicated here. But I don't know.
If Boise State had been chosen as an at-large team, I don't think Boise State would have earned the $26.4 million share, because the rules say the $26.4 million is earned only when there is an automatically qualifying team from a non-AQ conference. The rules do not indicate that an at-large team from a non-AQ conference earns that same $26.4 million. Rather, all at-large teams appear to get $6.1 million. So, my best guess is that if Boise State had been invited as an at-large team, the non-AQ conferences would have received their $13.2 million share, and Boise State's at-large berth would have earned an additional $6.1 million -- the same share as any other at-large team. If that is the case, then there was no cost difference between inviting Virginia Tech and inviting Boise State as an at-large team.
These rules are quoted from page 6 of the BCS media guide --
http://espn.go.com/i/ncf/bcs/2011BCSGuide2.pdf